pinewood derby

Would you use your tech prowess to cheat at the Pinewood Derby? When your kid brings home that minimalist kit and expects you to help engineer a car that can beat all the others in the gravity-powered race, the temptation is there. But luckily, there are some events that don’t include the kiddies and the need for parents to assume the proper moral posture. When the whole point of the Pinewood Derby is to cheat, then you pull out all the stops, and you might try building an electrodynamic suspension hoverboard car.

Fortunately for [ch00ftech], the team-building Derby sponsored by his employer is a little looser with the rules than the usual event. Loose enough perhaps to try a magnetically levitating car. The aluminum track provided a perfect surface to leverage Lenz’s Law. [ch00ftech] tried different arrangements of coils and drivers in an attempt to at least reduce the friction between car and track, if not outright levitate it. Sadly, time ran out and physics had others ideas, so [ch00ftech], intent on cheating by any means, tried spoofing the track timing system with a ridiculous front bumper of IR LEDs. But even that didn’t work in the end, and poor [ch00f]’s car wound up in sixth place.

So what could [ch00ftech] had done better? Was he on the right course with levitation? Or was spoofing the sensors likely to have worked with better optics? Or should he have resorted to jet propulsion or a propeller drive? How would you cheat at the Pinewood Derby?

Fail of the Week is a Hackaday column which celebrates failure as a learning tool. Help keep the fun rolling by writing about your own failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

There are a lot of reasons to consider reproducing. Tax breaks are near the top of the list, and a bizarre obligation to ensure the survival of the species following closely behind. The pinewood derby, though… Where else are you going to get a chance to spend hours polishing axles and weighing down bits of wood so they can roll faster?

The Lansing Makers Network has cub scouts around the shop, most likely goofing off while their fathers spend hours building their son’s pinewood derby racers. Where there’s a pinewood derby manufactory, there’s a need for a track to test these racers out.

The four-lane, 38-foot run was made out of five sections of cabinet plywood attached with 4″ lap joints. That’s the way to do it if you want a smooth running surface. The lanes are 1/4″ strips of maple plywood, and the last four feet of the track – after the finish line, of course – are a ramp that raises the lanes another 1/2″ above the ground. There’s very little need for a bunch of pillows or foam at the end of the track.

This is the 21st century, and no pinewood derby track would be complete without a few bits of electronics. The starting gate is activated with a push button. A solenoid keeps a quartet of pins in place until the race is started. When the start button is pressed, the solenoid releases, sending the cars on their way.

On their way down the ramp, the cars pass over an IR object sensor which records their starting time. Thanks to some more sensors at the finish line, the track records each car’s position in the race on a few seven-segment displays.

Every year, [ilektronx] and a few other guys get together and compete in a ‘no holds barred’ pinewood derby for kids of all ages. Of course this results in an immense amount of engineering to push a wooden block with wheels down a track, and [ilektronx]’s car is no exception. He won the competition with electronics from a remote control airplane bolted on to a piece of wood.

The electronics for [ilektronix]’s build are pretty much what you’d find in any small electric RC plane: a cheap transmitter / receiver combo sends commands to an ESC which powers a small brushless motor with a small LiPo battery.

Like all good pinewood derby cars, the success of [ilektronix]’s entry relied on the overall design. The wooden chassis cleverly hugs the raised guide in the track, and the slight downward angle of the propeller keeps the car from popping a wheelie when it is released from the starting line.

You can check out a video summary of the pinewood derby competition after the break. Also shown are a few of the other derby cars, including an amazing futuristic tank entry built by [Ken Cook]. [Ken] spent the better part of a year on his build, and the amazing detail of making his own tank treads by hand made him a shoe-in for the winner of the ‘style’ competition.

When it comes time to unwind at the Dyson design facility these engineers know how to do it right. Recently, the company challenged their engineers to a grown-up version of the Pinewood Derby in which they raced their own cars powered by a Dyson motor.

The video after the breaks shows a large collection of these time trials on a track made from upturned wooden pallets. Most of the vehicles are made from parts which we don’t recognize. But some of them are very familiar like our favorite hand dryer ever (seen above) and the iconic goldenrod manifold from the Dyson ball vacuum cleaner.

The course ends abruptly, as you can see in the last run of the video. There is one entry that included a human rider and he seems to be going nearly as fast as the riderless carriages are. The video cuts away before he hits the wall, but we can’t image he had the time to include brakes in that design.

Need some gears? Got a timing belt?

[filespace] sent in a neat build he stumbled upon: making gears with plywood and a timing belt. Just cut out a plywood disk and glue on a section of timing belt. There’s some math involved in getting all the teeth evenly placed around the perimeter, but nothing too bad. Also useful for wheels, we think.

Huge chess sets are cool, right up until you try to figure out where to store the pieces when they’re not being used. [Jayefuu] came up with a neat solution to this problem. His pieces are cut out of coroplast (that corrugated plastic stuff political campaign signs are made of), making it relatively inexpensive and just as fun as normal giant chess pieces on a tile floor.

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[Randy]’s son is in the cub scouts. Being the awesome father he is, [Randy] helped out with this year’s pinewood derby build. It’s a car shaped like a portal gun with the obligatory color-changing LED. The car won the ‘Can’t get more awesome’ award, but wheel misalignment kicked it out of the competition during qualifying rounds. Sad, that. Still awesome, though.

These people are giving you tools for free

Caltech professor [Yaser Abu-Mostafa] is teaching a Machine Learning class this semester. You can take this class as well, even if the second lecture started last Thursday.

Turning an Arduino into a speech synthesizer

[AlanFromJapan] sent in this product page for an Arduino-powered speech synthesizer. We’re probably looking at a relabeled ATmega328 with custom firmware here; to use it, you replace the micro in your Arduino Uno with this chip. The chip goes for about $10 USD here, so we’ll give it a week until someone has this proprietary firmware up on the Internet. There are English morphemes that aren’t in Japanese, so you can’t just ‘type in English’ and have it work. Here’s a video.

Six things in this links post. We’re feeling generous.

What would you build if you had a laser cutter? [Doug Miller] made a real, working fishing reel. No build log or files, but here’s a nice picture.

As a boy scout properly acculturated into the DIY philosophy, [Adam] really wanted to get his hands on the new Inventing merit badge. The merit badge required solving a problem, so of course a pinewood derby instant replay system was the obvious solution.

After thinking through a few solution paths like a radio-controlled camera that follows the cars, [Adam] settled on a system that would replay the pinewood derby cars crossing the finish line. [Adam]’s father found a cheap and readily available Playstation Eye camera that can record 60fps video for this task. [Adam] used a laser/photodiode/Arduino setup to detect when a car was crossing the finish line. A bit of Processing code supplied by his father records the relevant 60 frames of video and plays them at 5fps on a projector for the enthralled spectators.

We suspect that a similar setup could be used if [Adam]’s den wanted to try the rain gutter regatta or oft-forgotten space derby next year. Check out [Adam]’s instant replay system after the break, or join us in the comments for the inevitable argument over who had the best pinewood derby car.

Get your graphite and hike a wheel, [Aron Hoekstra] writes in to completely embarrass us with some excellent pinewood derby cars. In the pursuit of that extra something [Aron] consulted with his sons who came up with some cool ideas for cars, one Tron themed and the other basically a Wiimote with wheels! The official Pinewood derby rules say nothing about electronics, so as long as nothing helps the block-o-wood travel down the track faster, anything goes. This means you are free to load up whatever cool lights you want, but will have to earn your robotics merit badge some other way.

[Aron] Starts the builds by carving out the shape of the cars, each feature a hollowed out cavity underneath to accommodate the batteries and electronics. For the Tron Light Runner car, one continuous EL strip weaves in and out of the derby car’s body, and a single AAA battery runs the driver. [Aron] notes that it took around five feet of EL wire to cover the little car, which is two more than the driver is rated for. Fortunately the extra little bit of additional wire had little effect on its brightness.

The Wiimote car has detailed 3d buttons, a breadboard with a linear regulator, and PIC 16F628 driving blue LEDs. For the majority of the time the PIC simply runs a chase routine for the four LEDs, but [Aron] went through the trouble to program in the Wiimote’s start-up sequence!

Shown above the [Hokestra]’s work is my older brother’s pinewood derby car (top left) and my… potato rocket… thing… (top right) from many many years ago. I now seriously regret not considering LEDs! Although I think all that existed then was red, green and IR.